1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method, in which data based on image data are stored in a memory, and a recording medium having a program recorded thereon.
2. Description of Related Art
Recently, there has been widely used an image forming apparatus, such as a network type of copier, printer, MFP (multifunction peripherals), etc. which receives print data, namely, image data in a form of PDL (Page Description Language), produced by an external device, e.g., a PC (Personal Computer), through a network, e.g., a LAN, converts the received print data temporarily into data in an intermediate form (intermediate data) to store in a memory, reads the stored intermediate data sequentially to convert into bitmap data, and then prints out. The PDL typically includes PostScript™ and PCL (Printer Control Language).
There is a demand for higher throughput in such an image forming apparatus for an increase of print data according as printing process speed has become higher. The apparatus has to hold print data until the printing has been completed, because when a certain error occurs, printing has to be resumed from the page where the error occurred. Further, when a memory has not an enough empty area, the memory cannot store new data and a memory-over error resultantly occurs. Accordingly, memory capacity needs to be increased for processing large data simultaneously and higher cost results, which leads to a problem.
In order to avoid such an increase of memory capacity, there has been applied processing of compression or the like to data to be stored for decreasing the memory capacity, but such a method needs additional processing for compressing process, which causes the throughput to be reduced.
There has been also adopted a method to improve efficiency for using a memory by managing intermediate data and bitmap data in a common memory with use of a threshold value. However, with this method, data is just held according to a simple compared result of determination as to whether the empty area of the memory is larger than the threshold value, and processing stops until the memory secures an empty area larger than the threshold value. This also leads to a problem of reducing the throughput.
Further, JP 2004-82401A discloses such a printing apparatus for improving throughput with efficient use of a memory that identifies an interface through which print data are input, reads in information indicating the identified interface and jam-recovery information indicating validness/invalidness of a jam-recovering process set for the identified interface, secures a storing buffer area by reducing a memory area used as a work area to execute a normal jam-recovering process when the jam-recovering process is set valid according to the jam-recovery information, and uses the storing buffer as a work area or other operation area when set invalid.
However, in the above-described technique, according to whether the jam-recovering process, which is set for the interface that sent the print data, is valid or not, the printing apparatus changes methods of using the memory for effective use of the memory. When the jam-recovering process is set valid, the apparatus uses the memory not different from normal use, which results in processing stop because it waits for an empty area and cannot improve the throughput. That is, the apparatus changes a method of using a memory according to a condition set for an interface, or manages the memory depending on the interface, resulting in difficulty in improving throughput.